Gas-powered guns are well known. Nowadays they are used in mock combat. The object is to fire a paint pellet to strike a combatant, the released paint indicating a hit.
One example of such a gun is to be found in Canadian patent No. 1,264,128 issued on Jan. 2, 1990 and citing Aldo Perrone as the inventor. A lower barrel of the gun receives a paint pellet. An upper barrel receives a gas cartridge required to fire the pellet. The gas cartridge is automatically pierced and placed in communication with the gas flow channels when inserted into the upper barrel. A discharge valve located in the lower barrel receives pressurized gas from the cartridge. A trigger mechanism causes the valve to release the gas in a sudden burst through a low resistance flow path into the barrel upstream of the paint pellet.
The velocity of the paint pellet is preferably about 300 feet per second. Such velocities provide realistic play, but the impact of the projectile can be accommodated by conventional protective gear. The gun will be appropriately configured to produce that barrel velocity when operated with a gas cartridge with a fixed pressure rating. The pressure within the cartridge is effectively the pressure applied by the discharge valve momentarily to the paint pellet. Problems arise when the cartridge is exposed to high ambient temperatures. The gas pressure of the cartridge can increase dramatically, and the paint projectile may fire at an unexpectedly high velocity. Combatants are then exposed to serious risk of injury. Also, individuals, whether in mock combat or target competitions, are required to compete on an equal basis. Higher barrel velocities can provide an advantage to some, whether attributable to pressure increases in gas cartridges or variations between weapons.
Measures have been proposed to regulate projectile velocity in gas-powered guns. A velocity adjuster may be used. It obstructs the flow path between the discharge valve and the projectile, restricting gas flow. A set screw permits the degree of flow restriction to be adjusted and consequently the velocity attained by a projectile. However, projectile velocity remains dependent on the pressure of the gas source after initial setting of the adjuster. A significant change in source pressure in response to ambient temperatures produces a corresponding change in velocity. Another approach involves use of a spring-biased pressure relief valve. Basically, if pressure within the gun exceeds an adjustable threshold, gas is discharged to the environment. There are two shortcomings to such an approach. First, the pressure relief valve causes a pronounced hissing that is unacceptable in mock combat. Second, gas is simply wasted.
Such problems have long been recognized, but a satisfactory solution does not appear to have been proposed. The present invention addresses such problems.